The present invention relates to an Liquid Crystal Display (referred to as LCD, hereinafter) unit for illuminating characters and symbols by means of an LCD driver and, more particularly to an effective wiring art of signal conductors used in the LCD unit provided with a pict display section and a dot matrix display section, and an illuminating control method of the pict display section.
A conventional LCD unit has two types of display system, one is a pict display for displaying fixed characters, symbols and pictures and another is a dot matrix display where a plurality of cells are arranged in dot matrix and some cells are selected and illuminated to form a predetermined character by applying drive voltage to the selected cells. A certain model of the LCD unit has both the pict display section and the dot matrix display section.
FIG. 9 shows the LCD unit provided with both the dot matrix display section 31 and the pict display section 32 on its surface.
As FIG. 10 shows, signal conductors of those display sections, that is, the dot matrix display section 31 and the pict display section 32 comprise common signal conductors 1 to 15 connected to the row electrodes of the dot matrix display section 31 and the pict display section 32, and segment signal conductors 1 to 40 connected to the column electrodes of the dot matrix display section 31. These signal conductors elongate toward a connection terminal 33 for connecting an external device to the display sections 31 and 32, respectively.
With a conventional wiring of signal conductors, disposing the pict display section 32 between the dot matrix display section 31 and the connection terminal 33 as shown in FIG. 11 requires the segment signal conductors and common signal conductors connecting the dot matrix display section 31 and the connection terminal 33 to bypass the respective pict display sections 32. This results in very complicated wiring as a whole. Moreover in case the wiring space is limited, sufficient space for disposing the pict display section 32 between the dot matrix display section 31 and the connection terminal 33 cannot be obtained, thus restricting provision of the display section.
The Japanese Patent Application Laid-Open No. 31890 (1992) discloses a wiring method with decreased signal conductors as a whole by dividing a character string on one row of the dot matrix display section into a plurality of parts so that the segment signal conductor is shared by those divided parts of the character string.
In this art, as shown in FIG. 12, eight common signal conductors COMs 1 to 8 for a left half character string of the first row, eight common signal conductors COMs 9 to 16 for a right half character string of the first row, eight common signal conductors COMs 17 to 24 for a left half character string of the second row and eight common signal conductors COMs 25 to 32 for a right half character string of the second row are disposed. Segment signal conductors SEGs 1 to 50 for two left character strings of the first row and the second row, and the segment signal conductors SEGs 1 to 50 are shared by two right character strings of the first row and the second row. As a result, in case of displaying two rows (where a character with 5.times.8 dot matrix, 20 characters per a row), 32 lines of common signal conductors and 50 lines of segment signal conductors, totally 82 signal conductors are needed.
This invention has enabled to greatly reduce the number of necessary lines of signal conductors that has been 116 lines in a conventional art.
With this prior art, however, the wiring of signal conductors still requires to bypass the pict display section.